1. Field of the Invention
This invention relates to certain piperazinylbenzoheterocyclic compounds and to pharmaceutically acceptable salts thereof which are useful as antimicrobial agents, processes for preparing the same, and pharmaceutical compositions containing the piperazinylbenzoheterocyclic compound or salt thereof.
2. Description of the Prior Art
It is known that certain types of polyheterocyclic compounds exhibit antimicrobial activities. For example, U.S. Pat. No. 3,917,609 to Gerster et al. discloses substituted derivatives of 1,2-dihydro-6-oxo-6H-pyrrolo[3,2,1-ij]quinoline which are useful as antimicrobial agents or as intermediates for the preparation of antimicrobial agents.
Also, U.S. Pat. Nos. 3,896,131, 3,985,882, 3,969,463, 4,001,243 and 4,014,877 to Gerster et al. disclose 6,7-dihydro-1-oxo-1H,5H-benzo[ij]quinolizine derivatives having antimicrobial activities.
However, the piperazinylbenzoheterocyclic compounds of the present invention are structurally different from such quinoline and quinolizine compounds.